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openjdk/src/hotspot/share/services/threadService.cpp
Alex Menkov 406f1bc5b9 8357650: ThreadSnapshot to take snapshot of thread for thread dumps 
Co-authored-by: Alan Bateman <alanb@openjdk.org>
Co-authored-by: Alex Menkov <amenkov@openjdk.org>
Reviewed-by: sspitsyn, kevinw
2025-06-03 18:46:55 +00:00

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/*
* Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "classfile/javaClasses.inline.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc/shared/oopStorageSet.hpp"
#include "memory/heapInspection.hpp"
#include "memory/oopFactory.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "nmt/memTag.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/klass.inline.hpp"
#include "oops/method.inline.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oopHandle.inline.hpp"
#include "prims/jvmtiRawMonitor.hpp"
#include "prims/jvmtiThreadState.hpp"
#include "runtime/atomic.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/init.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/javaThread.inline.hpp"
#include "runtime/jniHandles.inline.hpp"
#include "runtime/objectMonitor.inline.hpp"
#include "runtime/synchronizer.inline.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threads.hpp"
#include "runtime/threadSMR.inline.hpp"
#include "runtime/vframe.inline.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vmOperations.hpp"
#include "services/threadService.hpp"
// TODO: we need to define a naming convention for perf counters
// to distinguish counters for:
// - standard JSR174 use
// - Hotspot extension (public and committed)
// - Hotspot extension (private/internal and uncommitted)
// Default is disabled.
bool ThreadService::_thread_monitoring_contention_enabled = false;
bool ThreadService::_thread_cpu_time_enabled = false;
bool ThreadService::_thread_allocated_memory_enabled = false;
PerfCounter* ThreadService::_total_threads_count = nullptr;
PerfVariable* ThreadService::_live_threads_count = nullptr;
PerfVariable* ThreadService::_peak_threads_count = nullptr;
PerfVariable* ThreadService::_daemon_threads_count = nullptr;
volatile int ThreadService::_atomic_threads_count = 0;
volatile int ThreadService::_atomic_daemon_threads_count = 0;
volatile jlong ThreadService::_exited_allocated_bytes = 0;
ThreadDumpResult* ThreadService::_threaddump_list = nullptr;
static const int INITIAL_ARRAY_SIZE = 10;
// OopStorage for thread stack sampling
static OopStorage* _thread_service_storage = nullptr;
void ThreadService::init() {
EXCEPTION_MARK;
// These counters are for java.lang.management API support.
// They are created even if -XX:-UsePerfData is set and in
// that case, they will be allocated on C heap.
_total_threads_count =
PerfDataManager::create_counter(JAVA_THREADS, "started",
PerfData::U_Events, CHECK);
_live_threads_count =
PerfDataManager::create_variable(JAVA_THREADS, "live",
PerfData::U_None, CHECK);
_peak_threads_count =
PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
PerfData::U_None, CHECK);
_daemon_threads_count =
PerfDataManager::create_variable(JAVA_THREADS, "daemon",
PerfData::U_None, CHECK);
if (os::is_thread_cpu_time_supported()) {
_thread_cpu_time_enabled = true;
}
_thread_allocated_memory_enabled = true; // Always on, so enable it
// Initialize OopStorage for thread stack sampling walking
_thread_service_storage = OopStorageSet::create_strong("ThreadService OopStorage",
mtServiceability);
}
void ThreadService::reset_peak_thread_count() {
// Acquire the lock to update the peak thread count
// to synchronize with thread addition and removal.
MutexLocker mu(Threads_lock);
_peak_threads_count->set_value(get_live_thread_count());
}
static bool is_hidden_thread(JavaThread *thread) {
// hide VM internal or JVMTI agent threads
return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
}
void ThreadService::add_thread(JavaThread* thread, bool daemon) {
assert(Threads_lock->owned_by_self(), "must have threads lock");
// Do not count hidden threads
if (is_hidden_thread(thread)) {
return;
}
_total_threads_count->inc();
_live_threads_count->inc();
Atomic::inc(&_atomic_threads_count);
int count = _atomic_threads_count;
if (count > _peak_threads_count->get_value()) {
_peak_threads_count->set_value(count);
}
if (daemon) {
_daemon_threads_count->inc();
Atomic::inc(&_atomic_daemon_threads_count);
}
}
void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
Atomic::dec(&_atomic_threads_count);
if (daemon) {
Atomic::dec(&_atomic_daemon_threads_count);
}
}
void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
assert(Threads_lock->owned_by_self(), "must have threads lock");
// Include hidden thread allcations in exited_allocated_bytes
ThreadService::incr_exited_allocated_bytes(thread->cooked_allocated_bytes());
// Do not count hidden threads
if (is_hidden_thread(thread)) {
return;
}
assert(!thread->is_terminated(), "must not be terminated");
if (!thread->is_exiting()) {
// We did not get here via JavaThread::exit() so current_thread_exiting()
// was not called, e.g., JavaThread::cleanup_failed_attach_current_thread().
decrement_thread_counts(thread, daemon);
}
int daemon_count = _atomic_daemon_threads_count;
int count = _atomic_threads_count;
// Counts are incremented at the same time, but atomic counts are
// decremented earlier than perf counts.
assert(_live_threads_count->get_value() > count,
"thread count mismatch %d : %d",
(int)_live_threads_count->get_value(), count);
_live_threads_count->dec(1);
if (daemon) {
assert(_daemon_threads_count->get_value() > daemon_count,
"thread count mismatch %d : %d",
(int)_daemon_threads_count->get_value(), daemon_count);
_daemon_threads_count->dec(1);
}
// Counts are incremented at the same time, but atomic counts are
// decremented earlier than perf counts.
assert(_daemon_threads_count->get_value() >= daemon_count,
"thread count mismatch %d : %d",
(int)_daemon_threads_count->get_value(), daemon_count);
assert(_live_threads_count->get_value() >= count,
"thread count mismatch %d : %d",
(int)_live_threads_count->get_value(), count);
assert(_live_threads_count->get_value() > 0 ||
(_live_threads_count->get_value() == 0 && count == 0 &&
_daemon_threads_count->get_value() == 0 && daemon_count == 0),
"thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
(int)_live_threads_count->get_value(), count,
(int)_daemon_threads_count->get_value(), daemon_count);
assert(_daemon_threads_count->get_value() > 0 ||
(_daemon_threads_count->get_value() == 0 && daemon_count == 0),
"thread counts should reach 0 at the same time, daemon %d,%d",
(int)_daemon_threads_count->get_value(), daemon_count);
}
void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
// Do not count hidden threads
if (is_hidden_thread(jt)) {
return;
}
assert(jt == JavaThread::current(), "Called by current thread");
assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
decrement_thread_counts(jt, daemon);
}
// FIXME: JVMTI should call this function
Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
assert(thread != nullptr, "should be non-null");
DEBUG_ONLY(Thread::check_for_dangling_thread_pointer(thread);)
// This function can be called on a target JavaThread that is not
// the caller and we are not at a safepoint. So it is possible for
// the waiting or pending condition to be over/stale and for the
// first stage of async deflation to clear the object field in
// the ObjectMonitor. It is also possible for the object to be
// inflated again and to be associated with a completely different
// ObjectMonitor by the time this object reference is processed
// by the caller.
ObjectMonitor *wait_obj = thread->current_waiting_monitor();
oop obj = nullptr;
if (wait_obj != nullptr) {
// thread is doing an Object.wait() call
obj = wait_obj->object();
} else {
ObjectMonitor *enter_obj = thread->current_pending_monitor();
if (enter_obj != nullptr) {
// thread is trying to enter() an ObjectMonitor.
obj = enter_obj->object();
}
}
Handle h(Thread::current(), obj);
return h;
}
bool ThreadService::set_thread_monitoring_contention(bool flag) {
MutexLocker m(Management_lock);
bool prev = _thread_monitoring_contention_enabled;
_thread_monitoring_contention_enabled = flag;
return prev;
}
bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
MutexLocker m(Management_lock);
bool prev = _thread_cpu_time_enabled;
_thread_cpu_time_enabled = flag;
return prev;
}
bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
MutexLocker m(Management_lock);
bool prev = _thread_allocated_memory_enabled;
_thread_allocated_memory_enabled = flag;
return prev;
}
void ThreadService::metadata_do(void f(Metadata*)) {
for (ThreadDumpResult* dump = _threaddump_list; dump != nullptr; dump = dump->next()) {
dump->metadata_do(f);
}
}
void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
MutexLocker ml(Management_lock);
if (_threaddump_list == nullptr) {
_threaddump_list = dump;
} else {
dump->set_next(_threaddump_list);
_threaddump_list = dump;
}
}
void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
MutexLocker ml(Management_lock);
ThreadDumpResult* prev = nullptr;
bool found = false;
for (ThreadDumpResult* d = _threaddump_list; d != nullptr; prev = d, d = d->next()) {
if (d == dump) {
if (prev == nullptr) {
_threaddump_list = dump->next();
} else {
prev->set_next(dump->next());
}
found = true;
break;
}
}
assert(found, "The threaddump result to be removed must exist.");
}
// Dump stack trace of threads specified in the given threads array.
// Returns StackTraceElement[][] each element is the stack trace of a thread in
// the corresponding entry in the given threads array
Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
int num_threads,
TRAPS) {
assert(num_threads > 0, "just checking");
ThreadDumpResult dump_result;
VM_ThreadDump op(&dump_result,
threads,
num_threads,
-1, /* entire stack */
false, /* with locked monitors */
false /* with locked synchronizers */);
VMThread::execute(&op);
// Allocate the resulting StackTraceElement[][] object
ResourceMark rm(THREAD);
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
ObjArrayKlass* ik = ObjArrayKlass::cast(k);
objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
objArrayHandle result_obj(THREAD, r);
int num_snapshots = dump_result.num_snapshots();
assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
int i = 0;
for (ThreadSnapshot* ts = dump_result.snapshots(); ts != nullptr; i++, ts = ts->next()) {
ThreadStackTrace* stacktrace = ts->get_stack_trace();
if (stacktrace == nullptr) {
// No stack trace
result_obj->obj_at_put(i, nullptr);
} else {
// Construct an array of java/lang/StackTraceElement object
Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
result_obj->obj_at_put(i, backtrace_h());
}
}
return result_obj;
}
void ThreadService::reset_contention_count_stat(JavaThread* thread) {
ThreadStatistics* stat = thread->get_thread_stat();
if (stat != nullptr) {
stat->reset_count_stat();
}
}
void ThreadService::reset_contention_time_stat(JavaThread* thread) {
ThreadStatistics* stat = thread->get_thread_stat();
if (stat != nullptr) {
stat->reset_time_stat();
}
}
bool ThreadService::is_virtual_or_carrier_thread(JavaThread* jt) {
oop threadObj = jt->threadObj();
if (threadObj != nullptr && threadObj->is_a(vmClasses::BaseVirtualThread_klass())) {
// a virtual thread backed by JavaThread
return true;
}
if (jt->is_vthread_mounted()) {
// carrier thread
return true;
}
return false;
}
// Find deadlocks involving raw monitors, object monitors and concurrent locks
// if concurrent_locks is true.
// We skip virtual thread carriers under the assumption that the current scheduler, ForkJoinPool,
// doesn't hold any locks while mounting a virtual thread, so any owned monitor (or j.u.c., lock for that matter)
// on that JavaThread must be owned by the virtual thread, and we don't support deadlock detection for virtual threads.
DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
// This code was modified from the original Threads::find_deadlocks code.
int globalDfn = 0, thisDfn;
ObjectMonitor* waitingToLockMonitor = nullptr;
JvmtiRawMonitor* waitingToLockRawMonitor = nullptr;
oop waitingToLockBlocker = nullptr;
bool blocked_on_monitor = false;
JavaThread *currentThread, *previousThread;
int num_deadlocks = 0;
// Initialize the depth-first-number for each JavaThread.
JavaThreadIterator jti(t_list);
for (JavaThread* jt = jti.first(); jt != nullptr; jt = jti.next()) {
if (!is_virtual_or_carrier_thread(jt)) {
jt->set_depth_first_number(-1);
}
}
DeadlockCycle* deadlocks = nullptr;
DeadlockCycle* last = nullptr;
DeadlockCycle* cycle = new DeadlockCycle();
for (JavaThread* jt = jti.first(); jt != nullptr; jt = jti.next()) {
if (is_virtual_or_carrier_thread(jt)) {
// skip virtual and carrier threads
continue;
}
if (jt->depth_first_number() >= 0) {
// this thread was already visited
continue;
}
thisDfn = globalDfn;
jt->set_depth_first_number(globalDfn++);
previousThread = jt;
currentThread = jt;
cycle->reset();
// The ObjectMonitor* can't be async deflated since we are at a safepoint.
// When there is a deadlock, all the monitors involved in the dependency
// cycle must be contended and heavyweight. So we only care about the
// heavyweight monitor a thread is waiting to lock.
waitingToLockMonitor = jt->current_pending_monitor();
// JVM TI raw monitors can also be involved in deadlocks, and we can be
// waiting to lock both a raw monitor and ObjectMonitor at the same time.
// It isn't clear how to make deadlock detection work correctly if that
// happens.
waitingToLockRawMonitor = jt->current_pending_raw_monitor();
if (concurrent_locks) {
waitingToLockBlocker = jt->current_park_blocker();
}
while (waitingToLockMonitor != nullptr ||
waitingToLockRawMonitor != nullptr ||
waitingToLockBlocker != nullptr) {
cycle->add_thread(currentThread);
// Give preference to the raw monitor
if (waitingToLockRawMonitor != nullptr) {
Thread* owner = waitingToLockRawMonitor->owner();
if (owner != nullptr && // the raw monitor could be released at any time
owner->is_Java_thread()) {
currentThread = JavaThread::cast(owner);
}
} else if (waitingToLockMonitor != nullptr) {
if (waitingToLockMonitor->has_owner()) {
currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor);
// If currentThread is null we would like to know if the owner
// is an unmounted vthread (no JavaThread*), because if it's not,
// it would mean the previous currentThread is blocked permanently
// and we should record this as a deadlock. Since there is currently
// no fast way to determine if the owner is indeed an unmounted
// vthread we never record this as a deadlock. Note: unless there
// is a bug in the VM, or a thread exits without releasing monitors
// acquired through JNI, null should imply an unmounted vthread owner.
}
} else {
if (concurrent_locks) {
if (waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
// This JavaThread (if there is one) is protected by the
// ThreadsListSetter in VM_FindDeadlocks::doit().
currentThread = threadObj != nullptr ? java_lang_Thread::thread(threadObj) : nullptr;
} else {
currentThread = nullptr;
}
}
}
if (currentThread == nullptr || is_virtual_or_carrier_thread(currentThread)) {
// No dependency on another thread
break;
}
if (currentThread->depth_first_number() < 0) {
// First visit to this thread
currentThread->set_depth_first_number(globalDfn++);
} else if (currentThread->depth_first_number() < thisDfn) {
// Thread already visited, and not on a (new) cycle
break;
} else if (currentThread == previousThread) {
// Self-loop, ignore
break;
} else {
// We have a (new) cycle
num_deadlocks++;
// add this cycle to the deadlocks list
if (deadlocks == nullptr) {
deadlocks = cycle;
} else {
last->set_next(cycle);
}
last = cycle;
cycle = new DeadlockCycle();
break;
}
previousThread = currentThread;
waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
if (concurrent_locks) {
waitingToLockBlocker = currentThread->current_park_blocker();
}
}
}
delete cycle;
return deadlocks;
}
ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(nullptr), _last(nullptr), _next(nullptr), _setter() {
// Create a new ThreadDumpResult object and append to the list.
// If GC happens before this function returns, Method*
// in the stack trace will be visited.
ThreadService::add_thread_dump(this);
}
ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(nullptr), _last(nullptr), _next(nullptr), _setter() {
// Create a new ThreadDumpResult object and append to the list.
// If GC happens before this function returns, oops
// will be visited.
ThreadService::add_thread_dump(this);
}
ThreadDumpResult::~ThreadDumpResult() {
ThreadService::remove_thread_dump(this);
// free all the ThreadSnapshot objects created during
// the VM_ThreadDump operation
ThreadSnapshot* ts = _snapshots;
while (ts != nullptr) {
ThreadSnapshot* p = ts;
ts = ts->next();
delete p;
}
}
ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
ThreadSnapshot* ts = new ThreadSnapshot();
link_thread_snapshot(ts);
return ts;
}
ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
ThreadSnapshot* ts = new ThreadSnapshot();
link_thread_snapshot(ts);
ts->initialize(t_list(), thread);
return ts;
}
void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
assert(_num_threads == 0 || _num_snapshots < _num_threads,
"_num_snapshots must be less than _num_threads");
_num_snapshots++;
if (_snapshots == nullptr) {
_snapshots = ts;
} else {
_last->set_next(ts);
}
_last = ts;
}
void ThreadDumpResult::metadata_do(void f(Metadata*)) {
for (ThreadSnapshot* ts = _snapshots; ts != nullptr; ts = ts->next()) {
ts->metadata_do(f);
}
}
ThreadsList* ThreadDumpResult::t_list() {
return _setter.list();
}
StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
_method = jvf->method();
_bci = jvf->bci();
_class_holder = OopHandle(_thread_service_storage, _method->method_holder()->klass_holder());
_locked_monitors = nullptr;
if (with_lock_info) {
Thread* current_thread = Thread::current();
ResourceMark rm(current_thread);
HandleMark hm(current_thread);
GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
int length = list->length();
if (length > 0) {
_locked_monitors = new (mtServiceability) GrowableArray<OopHandle>(length, mtServiceability);
for (int i = 0; i < length; i++) {
MonitorInfo* monitor = list->at(i);
assert(monitor->owner() != nullptr, "This monitor must have an owning object");
_locked_monitors->append(OopHandle(_thread_service_storage, monitor->owner()));
}
}
}
}
StackFrameInfo::~StackFrameInfo() {
if (_locked_monitors != nullptr) {
for (int i = 0; i < _locked_monitors->length(); i++) {
_locked_monitors->at(i).release(_thread_service_storage);
}
delete _locked_monitors;
}
_class_holder.release(_thread_service_storage);
}
void StackFrameInfo::metadata_do(void f(Metadata*)) {
f(_method);
}
void StackFrameInfo::print_on(outputStream* st) const {
ResourceMark rm;
java_lang_Throwable::print_stack_element(st, method(), bci());
int len = (_locked_monitors != nullptr ? _locked_monitors->length() : 0);
for (int i = 0; i < len; i++) {
oop o = _locked_monitors->at(i).resolve();
st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
}
}
// Iterate through monitor cache to find JNI locked monitors
class InflatedMonitorsClosure: public MonitorClosure {
private:
ThreadStackTrace* _stack_trace;
public:
InflatedMonitorsClosure(ThreadStackTrace* st) {
_stack_trace = st;
}
void do_monitor(ObjectMonitor* mid) {
oop object = mid->object();
if (!_stack_trace->is_owned_monitor_on_stack(object)) {
_stack_trace->add_jni_locked_monitor(object);
}
}
};
ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
_thread = t;
_frames = new (mtServiceability) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, mtServiceability);
_depth = 0;
_with_locked_monitors = with_locked_monitors;
if (_with_locked_monitors) {
_jni_locked_monitors = new (mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability);
} else {
_jni_locked_monitors = nullptr;
}
}
void ThreadStackTrace::add_jni_locked_monitor(oop object) {
_jni_locked_monitors->append(OopHandle(_thread_service_storage, object));
}
ThreadStackTrace::~ThreadStackTrace() {
for (int i = 0; i < _frames->length(); i++) {
delete _frames->at(i);
}
delete _frames;
if (_jni_locked_monitors != nullptr) {
for (int i = 0; i < _jni_locked_monitors->length(); i++) {
_jni_locked_monitors->at(i).release(_thread_service_storage);
}
delete _jni_locked_monitors;
}
}
void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth, ObjectMonitorsView* monitors, bool full) {
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
if (_thread->has_last_Java_frame()) {
RegisterMap reg_map(_thread,
RegisterMap::UpdateMap::include,
RegisterMap::ProcessFrames::include,
RegisterMap::WalkContinuation::skip);
ResourceMark rm(VMThread::vm_thread());
// If full, we want to print both vthread and carrier frames
vframe* start_vf = !full && _thread->is_vthread_mounted()
? _thread->carrier_last_java_vframe(&reg_map)
: _thread->last_java_vframe(&reg_map);
int count = 0;
for (vframe* f = start_vf; f; f = f->sender() ) {
if (maxDepth >= 0 && count == maxDepth) {
// Skip frames if more than maxDepth
break;
}
if (!full && f->is_vthread_entry()) {
break;
}
if (f->is_java_frame()) {
javaVFrame* jvf = javaVFrame::cast(f);
add_stack_frame(jvf);
count++;
} else {
// Ignore non-Java frames
}
}
}
if (_with_locked_monitors) {
// Iterate inflated monitors and find monitors locked by this thread
// that are not found in the stack, e.g. JNI locked monitors:
InflatedMonitorsClosure imc(this);
monitors->visit(&imc, _thread);
}
}
bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
bool found = false;
int num_frames = get_stack_depth();
for (int depth = 0; depth < num_frames; depth++) {
StackFrameInfo* frame = stack_frame_at(depth);
int len = frame->num_locked_monitors();
GrowableArray<OopHandle>* locked_monitors = frame->locked_monitors();
for (int j = 0; j < len; j++) {
oop monitor = locked_monitors->at(j).resolve();
assert(monitor != nullptr, "must be a Java object");
if (monitor == object) {
found = true;
break;
}
}
}
return found;
}
Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
InstanceKlass* ik = vmClasses::StackTraceElement_klass();
assert(ik != nullptr, "must be loaded in 1.4+");
// Allocate an array of java/lang/StackTraceElement object
objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
objArrayHandle backtrace(THREAD, ste);
for (int j = 0; j < _depth; j++) {
StackFrameInfo* frame = _frames->at(j);
methodHandle mh(THREAD, frame->method());
oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
backtrace->obj_at_put(j, element);
}
return backtrace;
}
void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
_frames->append(frame);
_depth++;
}
void ThreadStackTrace::metadata_do(void f(Metadata*)) {
int length = _frames->length();
for (int i = 0; i < length; i++) {
_frames->at(i)->metadata_do(f);
}
}
ConcurrentLocksDump::~ConcurrentLocksDump() {
if (_retain_map_on_free) {
return;
}
for (ThreadConcurrentLocks* t = _map; t != nullptr;) {
ThreadConcurrentLocks* tcl = t;
t = t->next();
delete tcl;
}
}
void ConcurrentLocksDump::dump_at_safepoint() {
// dump all locked concurrent locks
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
GrowableArray<oop>* aos_objects = new (mtServiceability) GrowableArray<oop>(INITIAL_ARRAY_SIZE, mtServiceability);
// Find all instances of AbstractOwnableSynchronizer
HeapInspection::find_instances_at_safepoint(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
aos_objects);
// Build a map of thread to its owned AQS locks
build_map(aos_objects);
delete aos_objects;
}
// build a map of JavaThread to all its owned AbstractOwnableSynchronizer
void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
int length = aos_objects->length();
for (int i = 0; i < length; i++) {
oop o = aos_objects->at(i);
oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
if (owner_thread_obj != nullptr) {
// See comments in ThreadConcurrentLocks to see how this
// JavaThread* is protected.
JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
assert(o->is_instance(), "Must be an instanceOop");
add_lock(thread, (instanceOop) o);
}
}
}
void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
if (tcl != nullptr) {
tcl->add_lock(o);
return;
}
// First owned lock found for this thread
tcl = new ThreadConcurrentLocks(thread);
tcl->add_lock(o);
if (_map == nullptr) {
_map = tcl;
} else {
_last->set_next(tcl);
}
_last = tcl;
}
ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
for (ThreadConcurrentLocks* tcl = _map; tcl != nullptr; tcl = tcl->next()) {
if (tcl->java_thread() == thread) {
return tcl;
}
}
return nullptr;
}
void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
st->print_cr(" Locked ownable synchronizers:");
ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
GrowableArray<OopHandle>* locks = (tcl != nullptr ? tcl->owned_locks() : nullptr);
if (locks == nullptr || locks->is_empty()) {
st->print_cr("\t- None");
st->cr();
return;
}
for (int i = 0; i < locks->length(); i++) {
oop obj = locks->at(i).resolve();
st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
}
st->cr();
}
ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
_thread = thread;
_owned_locks = new (mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability);
_next = nullptr;
}
ThreadConcurrentLocks::~ThreadConcurrentLocks() {
for (int i = 0; i < _owned_locks->length(); i++) {
_owned_locks->at(i).release(_thread_service_storage);
}
delete _owned_locks;
}
void ThreadConcurrentLocks::add_lock(instanceOop o) {
_owned_locks->append(OopHandle(_thread_service_storage, o));
}
ThreadStatistics::ThreadStatistics() {
_contended_enter_count = 0;
_monitor_wait_count = 0;
_sleep_count = 0;
_count_pending_reset = false;
_timer_pending_reset = false;
memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
}
oop ThreadSnapshot::threadObj() const { return _threadObj.resolve(); }
void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
_thread = thread;
oop threadObj = thread->threadObj();
_threadObj = OopHandle(_thread_service_storage, threadObj);
ThreadStatistics* stat = thread->get_thread_stat();
_contended_enter_ticks = stat->contended_enter_ticks();
_contended_enter_count = stat->contended_enter_count();
_monitor_wait_ticks = stat->monitor_wait_ticks();
_monitor_wait_count = stat->monitor_wait_count();
_sleep_ticks = stat->sleep_ticks();
_sleep_count = stat->sleep_count();
// If thread is still attaching then threadObj will be null.
_thread_status = threadObj == nullptr ? JavaThreadStatus::NEW
: java_lang_Thread::get_thread_status(threadObj);
_is_suspended = thread->is_suspended();
_is_in_native = (thread->thread_state() == _thread_in_native);
Handle obj = ThreadService::get_current_contended_monitor(thread);
oop blocker_object = nullptr;
oop blocker_object_owner = nullptr;
if (thread->is_vthread_mounted() && thread->vthread() != threadObj) { // ThreadSnapshot only captures platform threads
_thread_status = JavaThreadStatus::IN_OBJECT_WAIT;
oop vthread = thread->vthread();
assert(vthread != nullptr, "");
blocker_object = vthread;
blocker_object_owner = vthread;
} else if (_thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER ||
_thread_status == JavaThreadStatus::IN_OBJECT_WAIT ||
_thread_status == JavaThreadStatus::IN_OBJECT_WAIT_TIMED) {
if (obj() == nullptr) {
// monitor no longer exists; thread is not blocked
_thread_status = JavaThreadStatus::RUNNABLE;
} else {
blocker_object = obj();
JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
if ((owner == nullptr && _thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER)
|| (owner != nullptr && owner->is_attaching_via_jni())) {
// ownership information of the monitor is not available
// (may no longer be owned or releasing to some other thread)
// make this thread in RUNNABLE state.
// And when the owner thread is in attaching state, the java thread
// is not completely initialized. For example thread name and id
// and may not be set, so hide the attaching thread.
_thread_status = JavaThreadStatus::RUNNABLE;
blocker_object = nullptr;
} else if (owner != nullptr) {
blocker_object_owner = owner->threadObj();
}
}
} else if (_thread_status == JavaThreadStatus::PARKED || _thread_status == JavaThreadStatus::PARKED_TIMED) {
blocker_object = thread->current_park_blocker();
if (blocker_object != nullptr && blocker_object->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(blocker_object);
}
}
if (blocker_object != nullptr) {
_blocker_object = OopHandle(_thread_service_storage, blocker_object);
}
if (blocker_object_owner != nullptr) {
_blocker_object_owner = OopHandle(_thread_service_storage, blocker_object_owner);
}
}
oop ThreadSnapshot::blocker_object() const { return _blocker_object.resolve(); }
oop ThreadSnapshot::blocker_object_owner() const { return _blocker_object_owner.resolve(); }
ThreadSnapshot::~ThreadSnapshot() {
_blocker_object.release(_thread_service_storage);
_blocker_object_owner.release(_thread_service_storage);
_threadObj.release(_thread_service_storage);
delete _stack_trace;
delete _concurrent_locks;
}
void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors,
ObjectMonitorsView* monitors, bool full) {
_stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
_stack_trace->dump_stack_at_safepoint(max_depth, monitors, full);
}
void ThreadSnapshot::metadata_do(void f(Metadata*)) {
if (_stack_trace != nullptr) {
_stack_trace->metadata_do(f);
}
}
DeadlockCycle::DeadlockCycle() {
_threads = new (mtServiceability) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, mtServiceability);
_next = nullptr;
}
DeadlockCycle::~DeadlockCycle() {
delete _threads;
}
void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
st->cr();
st->print_cr("Found one Java-level deadlock:");
st->print("=============================");
JavaThread* currentThread;
JvmtiRawMonitor* waitingToLockRawMonitor;
oop waitingToLockBlocker;
int len = _threads->length();
for (int i = 0; i < len; i++) {
currentThread = _threads->at(i);
// The ObjectMonitor* can't be async deflated since we are at a safepoint.
ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor();
waitingToLockRawMonitor = currentThread->current_pending_raw_monitor();
waitingToLockBlocker = currentThread->current_park_blocker();
st->cr();
st->print_cr("\"%s\":", currentThread->name());
const char* owner_desc = ",\n which is held by";
// Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor
// sets the current pending monitor, it is possible to then see a pending raw monitor as well.
if (waitingToLockRawMonitor != nullptr) {
st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor));
Thread* owner = waitingToLockRawMonitor->owner();
// Could be null as the raw monitor could be released at any time if held by non-JavaThread
if (owner != nullptr) {
if (owner->is_Java_thread()) {
currentThread = JavaThread::cast(owner);
st->print_cr("%s \"%s\"", owner_desc, currentThread->name());
} else {
st->print_cr(",\n which has now been released");
}
} else {
st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner));
}
}
if (waitingToLockMonitor != nullptr) {
st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
oop obj = waitingToLockMonitor->object();
st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
obj->klass()->external_name());
if (!currentThread->current_pending_monitor_is_from_java()) {
owner_desc = "\n in JNI, which is held by";
}
currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor);
if (currentThread == nullptr) {
// The deadlock was detected at a safepoint so the JavaThread
// that owns waitingToLockMonitor should be findable, but
// if it is not findable, then the previous currentThread is
// blocked permanently.
st->print_cr("%s UNKNOWN_owner_addr=" INT64_FORMAT, owner_desc,
waitingToLockMonitor->owner());
continue;
}
} else {
st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
p2i(waitingToLockBlocker),
waitingToLockBlocker->klass()->external_name());
assert(waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
"Must be an AbstractOwnableSynchronizer");
oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
currentThread = java_lang_Thread::thread(ownerObj);
assert(currentThread != nullptr, "AbstractOwnableSynchronizer owning thread is unexpectedly null");
}
st->print_cr("%s \"%s\"", owner_desc, currentThread->name());
}
st->cr();
// Print stack traces
bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
JavaMonitorsInStackTrace = true;
st->print_cr("Java stack information for the threads listed above:");
st->print_cr("===================================================");
for (int j = 0; j < len; j++) {
currentThread = _threads->at(j);
st->print_cr("\"%s\":", currentThread->name());
currentThread->print_stack_on(st);
}
JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
}
ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
bool include_jvmti_agent_threads,
bool include_jni_attaching_threads,
bool include_bound_virtual_threads) {
assert(cur_thread == Thread::current(), "Check current thread");
int init_size = ThreadService::get_live_thread_count();
_threads_array = new GrowableArray<instanceHandle>(init_size);
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
// skips JavaThreads in the process of exiting
// and also skips VM internal JavaThreads
// Threads in _thread_new or _thread_new_trans state are included.
// i.e. threads have been started but not yet running.
if (jt->threadObj() == nullptr ||
jt->is_exiting() ||
!java_lang_Thread::is_alive(jt->threadObj()) ||
jt->is_hidden_from_external_view()) {
continue;
}
// skip agent threads
if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
continue;
}
// skip jni threads in the process of attaching
if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
continue;
}
// skip instances of BoundVirtualThread
if (!include_bound_virtual_threads && jt->threadObj()->is_a(vmClasses::BoundVirtualThread_klass())) {
continue;
}
instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
_threads_array->append(h);
}
}
// jdk.internal.vm.ThreadSnapshot support
#if INCLUDE_JVMTI
class GetThreadSnapshotClosure: public HandshakeClosure {
private:
static OopStorage* oop_storage() {
assert(_thread_service_storage != nullptr, "sanity");
return _thread_service_storage;
}
public:
struct OwnedLock {
// should be synced with ordinals of jdk.internal.vm.ThreadSnapshot.OwnedLockType enum
enum Type {
NOTHING = -1,
LOCKED = 0,
ELIMINATED = 1,
};
int _frame_depth;
Type _type;
// synchronization object (when type == LOCKED) or its klass (type == ELIMINATED)
OopHandle _obj;
OwnedLock(int depth, Type type, OopHandle obj): _frame_depth(depth), _type(type), _obj(obj) {}
OwnedLock(): _frame_depth(0), _type(NOTHING), _obj(nullptr) {}
};
struct Blocker {
// should be synced with ordinals of jdk.internal.vm.ThreadSnapshot.BlockerLockType enum
enum Type {
NOTHING = -1,
PARK_BLOCKER = 0,
WAITING_TO_LOCK = 1,
WAITING_ON = 2,
};
Type _type;
// park blocker or an object the thread waiting on/trying to lock
OopHandle _obj;
Blocker(Type type, OopHandle obj): _type(type), _obj(obj) {}
Blocker(): _type(NOTHING), _obj(nullptr) {}
bool is_empty() const {
return _type == NOTHING;
}
};
Handle _thread_h;
JavaThread* _java_thread;
int _frame_count; // length of _methods and _bcis arrays
GrowableArray<Method*>* _methods;
GrowableArray<int>* _bcis;
JavaThreadStatus _thread_status;
OopHandle _thread_name;
GrowableArray<OwnedLock>* _locks;
Blocker _blocker;
GetThreadSnapshotClosure(Handle thread_h, JavaThread* java_thread):
HandshakeClosure("GetThreadSnapshotClosure"),
_thread_h(thread_h), _java_thread(java_thread),
_frame_count(0), _methods(nullptr), _bcis(nullptr),
_thread_status(), _thread_name(nullptr),
_locks(nullptr), _blocker() {
}
virtual ~GetThreadSnapshotClosure() {
delete _methods;
delete _bcis;
_thread_name.release(oop_storage());
if (_locks != nullptr) {
for (int i = 0; i < _locks->length(); i++) {
_locks->at(i)._obj.release(oop_storage());
}
delete _locks;
}
_blocker._obj.release(oop_storage());
}
private:
void detect_locks(javaVFrame* jvf, int depth) {
Thread* current = Thread::current();
if (depth == 0 && _blocker.is_empty()) {
// If this is the first frame and it is java.lang.Object.wait(...)
// then print out the receiver.
if (jvf->method()->name() == vmSymbols::wait_name() &&
jvf->method()->method_holder()->name() == vmSymbols::java_lang_Object()) {
OopHandle lock_object;
StackValueCollection* locs = jvf->locals();
if (!locs->is_empty()) {
StackValue* sv = locs->at(0);
if (sv->type() == T_OBJECT) {
Handle o = locs->at(0)->get_obj();
lock_object = OopHandle(oop_storage(), o());
}
}
_blocker = Blocker(Blocker::WAITING_ON, lock_object);
}
}
GrowableArray<MonitorInfo*>* mons = jvf->monitors();
if (!mons->is_empty()) {
for (int index = (mons->length() - 1); index >= 0; index--) {
MonitorInfo* monitor = mons->at(index);
if (monitor->eliminated() && jvf->is_compiled_frame()) { // Eliminated in compiled code
if (monitor->owner_is_scalar_replaced()) {
Klass* k = java_lang_Class::as_Klass(monitor->owner_klass());
_locks->push(OwnedLock(depth, OwnedLock::ELIMINATED, OopHandle(oop_storage(), k->klass_holder())));
} else {
Handle owner(current, monitor->owner());
if (owner.not_null()) {
Klass* k = owner->klass();
_locks->push(OwnedLock(depth, OwnedLock::ELIMINATED, OopHandle(oop_storage(), k->klass_holder())));
}
}
continue;
}
if (monitor->owner() != nullptr) {
// the monitor is associated with an object, i.e., it is locked
if (depth == 0 && _blocker.is_empty()) {
ObjectMonitor* pending_moninor = java_lang_VirtualThread::is_instance(_thread_h())
? java_lang_VirtualThread::current_pending_monitor(_thread_h())
: jvf->thread()->current_pending_monitor();
markWord mark = monitor->owner()->mark();
// The first stage of async deflation does not affect any field
// used by this comparison so the ObjectMonitor* is usable here.
if (mark.has_monitor()) {
ObjectMonitor* mon = ObjectSynchronizer::read_monitor(current, monitor->owner(), mark);
if (// if the monitor is null we must be in the process of locking
mon == nullptr ||
// we have marked ourself as pending on this monitor
mon == pending_moninor ||
// we are not the owner of this monitor
(_java_thread != nullptr && !mon->is_entered(_java_thread))) {
_blocker = Blocker(Blocker::WAITING_TO_LOCK, OopHandle(oop_storage(), monitor->owner()));
continue; // go to next monitor
}
}
}
_locks->push(OwnedLock(depth, OwnedLock::LOCKED, OopHandle(oop_storage(), monitor->owner())));
}
}
}
}
public:
void do_thread(Thread* th) override {
Thread* current = Thread::current();
bool is_virtual = java_lang_VirtualThread::is_instance(_thread_h());
if (_java_thread != nullptr) {
if (is_virtual) {
// mounted vthread, use carrier thread state
oop carrier_thread = java_lang_VirtualThread::carrier_thread(_thread_h());
_thread_status = java_lang_Thread::get_thread_status(carrier_thread);
} else {
_thread_status = java_lang_Thread::get_thread_status(_thread_h());
}
} else {
// unmounted vthread
int vt_state = java_lang_VirtualThread::state(_thread_h());
_thread_status = java_lang_VirtualThread::map_state_to_thread_status(vt_state);
}
_thread_name = OopHandle(oop_storage(), java_lang_Thread::name(_thread_h()));
if (_java_thread != nullptr && !_java_thread->has_last_Java_frame()) {
// stack trace is empty
return;
}
bool vthread_carrier = !is_virtual && (_java_thread != nullptr) && (_java_thread->vthread_continuation() != nullptr);
oop park_blocker = java_lang_Thread::park_blocker(_thread_h());
if (park_blocker != nullptr) {
_blocker = Blocker(Blocker::PARK_BLOCKER, OopHandle(oop_storage(), park_blocker));
}
ResourceMark rm(current);
HandleMark hm(current);
const int max_depth = MaxJavaStackTraceDepth;
const bool skip_hidden = !ShowHiddenFrames;
// Pick minimum length that will cover most cases
int init_length = 64;
_methods = new (mtInternal) GrowableArray<Method*>(init_length, mtInternal);
_bcis = new (mtInternal) GrowableArray<int>(init_length, mtInternal);
_locks = new (mtInternal) GrowableArray<OwnedLock>(init_length, mtInternal);
int total_count = 0;
vframeStream vfst(_java_thread != nullptr
? vframeStream(_java_thread, false, true, vthread_carrier)
: vframeStream(java_lang_VirtualThread::continuation(_thread_h())));
for (;
!vfst.at_end() && (max_depth == 0 || max_depth != total_count);
vfst.next()) {
detect_locks(vfst.asJavaVFrame(), total_count);
if (skip_hidden && (vfst.method()->is_hidden() ||
vfst.method()->is_continuation_enter_intrinsic())) {
continue;
}
_methods->push(vfst.method());
_bcis->push(vfst.bci());
total_count++;
}
_frame_count = total_count;
}
};
class jdk_internal_vm_ThreadLock: AllStatic {
static bool _inited;
static int _depth_offset;
static int _typeOrdinal_offset;
static int _obj_offset;
static void compute_offsets(InstanceKlass* klass, TRAPS) {
JavaClasses::compute_offset(_depth_offset, klass, "depth", vmSymbols::int_signature(), false);
JavaClasses::compute_offset(_typeOrdinal_offset, klass, "typeOrdinal", vmSymbols::int_signature(), false);
JavaClasses::compute_offset(_obj_offset, klass, "obj", vmSymbols::object_signature(), false);
}
public:
static void init(InstanceKlass* klass, TRAPS) {
if (!_inited) {
compute_offsets(klass, CHECK);
_inited = true;
}
}
static Handle create(InstanceKlass* klass, int depth, int type_ordinal, OopHandle obj, TRAPS) {
init(klass, CHECK_NH);
Handle result = klass->allocate_instance_handle(CHECK_NH);
result->int_field_put(_depth_offset, depth);
result->int_field_put(_typeOrdinal_offset, type_ordinal);
result->obj_field_put(_obj_offset, obj.resolve());
return result;
}
};
bool jdk_internal_vm_ThreadLock::_inited = false;
int jdk_internal_vm_ThreadLock::_depth_offset;
int jdk_internal_vm_ThreadLock::_typeOrdinal_offset;
int jdk_internal_vm_ThreadLock::_obj_offset;
class jdk_internal_vm_ThreadSnapshot: AllStatic {
static bool _inited;
static int _name_offset;
static int _threadStatus_offset;
static int _carrierThread_offset;
static int _stackTrace_offset;
static int _locks_offset;
static int _blockerTypeOrdinal_offset;
static int _blockerObject_offset;
static void compute_offsets(InstanceKlass* klass, TRAPS) {
JavaClasses::compute_offset(_name_offset, klass, "name", vmSymbols::string_signature(), false);
JavaClasses::compute_offset(_threadStatus_offset, klass, "threadStatus", vmSymbols::int_signature(), false);
JavaClasses::compute_offset(_carrierThread_offset, klass, "carrierThread", vmSymbols::thread_signature(), false);
JavaClasses::compute_offset(_stackTrace_offset, klass, "stackTrace", vmSymbols::java_lang_StackTraceElement_array(), false);
JavaClasses::compute_offset(_locks_offset, klass, "locks", vmSymbols::jdk_internal_vm_ThreadLock_array(), false);
JavaClasses::compute_offset(_blockerTypeOrdinal_offset, klass, "blockerTypeOrdinal", vmSymbols::int_signature(), false);
JavaClasses::compute_offset(_blockerObject_offset, klass, "blockerObject", vmSymbols::object_signature(), false);
}
public:
static void init(InstanceKlass* klass, TRAPS) {
if (!_inited) {
compute_offsets(klass, CHECK);
_inited = true;
}
}
static Handle allocate(InstanceKlass* klass, TRAPS) {
init(klass, CHECK_NH);
Handle h_k = klass->allocate_instance_handle(CHECK_NH);
return h_k;
}
static void set_name(oop snapshot, oop name) {
snapshot->obj_field_put(_name_offset, name);
}
static void set_thread_status(oop snapshot, int status) {
snapshot->int_field_put(_threadStatus_offset, status);
}
static void set_carrier_thread(oop snapshot, oop carrier_thread) {
snapshot->obj_field_put(_carrierThread_offset, carrier_thread);
}
static void set_stack_trace(oop snapshot, oop trace) {
snapshot->obj_field_put(_stackTrace_offset, trace);
}
static void set_locks(oop snapshot, oop locks) {
snapshot->obj_field_put(_locks_offset, locks);
}
static void set_blocker(oop snapshot, int type_ordinal, oop lock) {
snapshot->int_field_put(_blockerTypeOrdinal_offset, type_ordinal);
snapshot->obj_field_put(_blockerObject_offset, lock);
}
};
bool jdk_internal_vm_ThreadSnapshot::_inited = false;
int jdk_internal_vm_ThreadSnapshot::_name_offset;
int jdk_internal_vm_ThreadSnapshot::_threadStatus_offset;
int jdk_internal_vm_ThreadSnapshot::_carrierThread_offset;
int jdk_internal_vm_ThreadSnapshot::_stackTrace_offset;
int jdk_internal_vm_ThreadSnapshot::_locks_offset;
int jdk_internal_vm_ThreadSnapshot::_blockerTypeOrdinal_offset;
int jdk_internal_vm_ThreadSnapshot::_blockerObject_offset;
oop ThreadSnapshotFactory::get_thread_snapshot(jobject jthread, TRAPS) {
ThreadsListHandle tlh(THREAD);
ResourceMark rm(THREAD);
HandleMark hm(THREAD);
Handle thread_h(THREAD, JNIHandles::resolve(jthread));
// wrapper to auto delete JvmtiVTMSTransitionDisabler
class TransitionDisabler {
JvmtiVTMSTransitionDisabler* _transition_disabler;
public:
TransitionDisabler(): _transition_disabler(nullptr) {}
~TransitionDisabler() {
reset();
}
void init(jobject jthread) {
_transition_disabler = new (mtInternal) JvmtiVTMSTransitionDisabler(jthread);
}
void reset() {
if (_transition_disabler != nullptr) {
delete _transition_disabler;
_transition_disabler = nullptr;
}
}
} transition_disabler;
JavaThread* java_thread = nullptr;
bool is_virtual = java_lang_VirtualThread::is_instance(thread_h());
Handle carrier_thread;
if (is_virtual) {
// 1st need to disable mount/unmount transitions
transition_disabler.init(jthread);
carrier_thread = Handle(THREAD, java_lang_VirtualThread::carrier_thread(thread_h()));
if (carrier_thread != nullptr) {
java_thread = java_lang_Thread::thread(carrier_thread());
}
} else {
java_thread = java_lang_Thread::thread(thread_h());
}
// Handshake with target
GetThreadSnapshotClosure cl(thread_h, java_thread);
if (java_thread == nullptr) {
// unmounted vthread, execute on the current thread
cl.do_thread(nullptr);
} else {
Handshake::execute(&cl, &tlh, java_thread);
}
// all info is collected, can enable transitions.
transition_disabler.reset();
// StackTrace
InstanceKlass* ste_klass = vmClasses::StackTraceElement_klass();
assert(ste_klass != nullptr, "must be loaded");
objArrayHandle trace = oopFactory::new_objArray_handle(ste_klass, cl._frame_count, CHECK_NULL);
for (int i = 0; i < cl._frame_count; i++) {
methodHandle method(THREAD, cl._methods->at(i));
oop element = java_lang_StackTraceElement::create(method, cl._bcis->at(i), CHECK_NULL);
trace->obj_at_put(i, element);
}
// Locks
Symbol* lock_sym = vmSymbols::jdk_internal_vm_ThreadLock();
Klass* lock_k = SystemDictionary::resolve_or_fail(lock_sym, true, CHECK_NULL);
InstanceKlass* lock_klass = InstanceKlass::cast(lock_k);
objArrayHandle locks;
if (cl._locks != nullptr && cl._locks->length() > 0) {
locks = oopFactory::new_objArray_handle(lock_klass, cl._locks->length(), CHECK_NULL);
for (int n = 0; n < cl._locks->length(); n++) {
GetThreadSnapshotClosure::OwnedLock* lock_info = cl._locks->adr_at(n);
Handle lock = jdk_internal_vm_ThreadLock::create(lock_klass,
lock_info->_frame_depth, lock_info->_type, lock_info->_obj, CHECK_NULL);
locks->obj_at_put(n, lock());
}
}
// call static StackTraceElement[] StackTraceElement.of(StackTraceElement[] stackTrace)
// to properly initialize STEs.
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
ste_klass,
vmSymbols::java_lang_StackTraceElement_of_name(),
vmSymbols::java_lang_StackTraceElement_of_signature(),
trace,
CHECK_NULL);
// the method return the same trace array
Symbol* snapshot_klass_name = vmSymbols::jdk_internal_vm_ThreadSnapshot();
Klass* snapshot_klass = SystemDictionary::resolve_or_fail(snapshot_klass_name, true, CHECK_NULL);
if (snapshot_klass->should_be_initialized()) {
snapshot_klass->initialize(CHECK_NULL);
}
Handle snapshot = jdk_internal_vm_ThreadSnapshot::allocate(InstanceKlass::cast(snapshot_klass), CHECK_NULL);
jdk_internal_vm_ThreadSnapshot::set_name(snapshot(), cl._thread_name.resolve());
jdk_internal_vm_ThreadSnapshot::set_thread_status(snapshot(), (int)cl._thread_status);
jdk_internal_vm_ThreadSnapshot::set_carrier_thread(snapshot(), carrier_thread());
jdk_internal_vm_ThreadSnapshot::set_stack_trace(snapshot(), trace());
jdk_internal_vm_ThreadSnapshot::set_locks(snapshot(), locks());
if (!cl._blocker.is_empty()) {
jdk_internal_vm_ThreadSnapshot::set_blocker(snapshot(), cl._blocker._type, cl._blocker._obj.resolve());
}
return snapshot();
}
#endif // INCLUDE_JVMTI
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